This study will entail: 1) investigations of the cyclopentenyl and 5'-phosphonate analogs of the interferon-induced 2',5'-oliogoadenylate as specific inhibitors of 2',5'-oligo(A) phosphodiesterase, and 2) determination of the mechanism of the potentiation produced by poly (I).poly(C) and its derivatives on the antitumor activity of immune interferon (IFN-Gamma). This will include investigating the role of transcription and cellular oncogene expression by the synergistic combination of poly (I).poly(C) and IFN-Gamma in human colon carcinoma cell lines HT-29 and BE.